When civilian life proves too dull for Major Wilbrahams, he contacts Parker Pyne to escape his boredom. Pyne's assistant arranges a chance meeting with the beautiful Freda Clegg and the two join forces, but on leaving for Africa they encounter more than they had bargained for.

At a séance, Sir Alington, a venerable expert of the mental condition, is pestered by Mrs. Eversleigh about the importance of the sixth sense. Soon, a young man named Dermot is drawn in and tells them both about the sixth sense he experiences, a red signal that spells danger. He is about to tell them of the last time he saw the red signal when he stops himself. The last time he had the signal was earlier that very evening. But how could there be danger at a simple gathering of old friends?

James has found himself at the fashionable resort Kimpton-on-Sea, all due to the persuasion of his girlfriend, Grace, who during the last few months of their courtship has become more difficult to deal with. Among the upper echelons of society, including the Rajah of Maraputna, James feels disgruntled and out of place. Eager to both irritate and win over Grace, James bypasses the queue to the changing rooms and ducks into the private huts on the beach so that he can be the first into the sea. It is only later that he realizes he has accidentally come into possession of a very valuable and sought-after object.

Just as boredom is setting in on his long trip by motor coach across the desert to Baghdad, Mr. Parker Pyne reads about the case of the missing Mr. Long, the famous defaulting financier who, as the papers would have it, is in South America. Another member of his party, Captain Smethurst, tells Pyne that he is worried about something. But before he can tell Pyne what it is, he is found dead, with no visible wound. Pyne must piece together what happened from various clues, including scraps of conversation overheard back in Damascus.

At Mr. and Mrs. Unkerton's party in Greenway's House, Mr. Satterthwaite learns of a haunted window: No matter how many times it is replaced, it always contains the image of a gentleman in a plumed hat. When gunshots are heard, Satterthwaite finds that two of the guests have been shot dead, which is shortly followed by a sighting of the gentleman in the newly-replaced windowpane. Can Mr. Quin shed light on the mystery?

Sane and sensible Edward Robinson secretly dreams of fast cars, adventurous women, and danger, but his fiancée, Maud, keeps him grounded in reality. When Edward wins money in a newspaper competition, he immediately buys the sleek red car of his dreams without telling Maud. Adventure swiftly ensues, as he is embroiled in high-society scandals that lead him to a significant transformation.

Mr. Parker Pyne is having trouble trying to get to Beirut, what with his rusty linguistic skills and the less-than-comfortable traveling arrangements. But, with the help of a German pilot, Herr Schlagel, he is soon able to get his bearings. Herr Schlagel confesses that his thoughts are dominated by the mysterious and sudden death of one of his last passengers, who was in the company of Lady Esther from the House of Shiraz. Taking the initiative, Pyne writes to Lady Esther offering his services. When he arrives at the House of Shiraz, he waits to see what the infamously mad Lady Esther has to say for herself....

Mrs. Packington felt alone, helpless, and utterly forlorn. But her life changed when she stumbled upon an advertisement in the Times that read: "Are you happy? If not, consult Mr. Parker Pyne." Equally adept at putting together the fragments of a murder mystery or the pieces of a broken marriage, Mr. Parker Pyne is possibly the world's most unconventional private investigator. Armed with just his intuitive knowledge of human nature, he is an Englishman abroad, traveling the globe to solve and undo crime and misdemeanor.

When Mr. Satterthwaite visits a new exhibit at the Harchester Galleries, there is one painting that bears an unusual likeness to a mysterious acquaintance of his, Mr. Quin. In one bold move he purchases the canvas on the spot, and in another invites the artist of "The Dead Harlequin" to dine with him that night, with an empty place at the table set for Mr. Quin. Dinner conversation soon turns to the setting of "The Dead Harlequin", the doomed and ghostly house Charnley, where many have perished under tragic circumstances.

Mystery writer Anthony Eastwood is lured to the crime scene of a faked murder, where two individuals masquerading as police officers arrest him and charge him with murder. As the phony police officers escort Mr. Eastwood home, the true goal of the masquerade becomes apparent.

Jane Cleveland is in desperate need of a job, and when she sees an ad for a woman of her description needed to impersonate a grand duchess, she cannot believe her luck. The royal retainers tell Jane that the job will be dangerous because attempts have been made on the Grand Duchess Pauline's life, but this only serves to make the job more appealing. Jane's disguise initially goes according to plan, but when she is kidnapped and drugged, it appears that her new employers are not all that they seem....

Mr. Satterthwaite and Colonel Melrose are comfortably ensconced in the Colonel's study when the phone suddenly rings. Someone has been murdered, and, as the county chief constable, the Colonel lets Satterthwaite accompany him to the scene of the crime. The two of them have opposing opinions on why Sir James Dwighton has been bashed over the head with a blunt instrument. Rumor had it that red-haired beauty Laura Dwighton and her guest, the very attractive Mr. Paul Delangua, were engaged in an illicit affair, and Paul was thrown out by the disgruntled Sir James. But the facts of the murder all seem to add up too nicely....

Hercule Poirot is about to tuck into a very traditional English supper with his old friend Bonnington when a lone diner sparks his interest. Like clockwork, the man has eaten at the restaurant on Thursdays and Tuesdays for the last 10 years, but no one on the staff knows his name. When "Old Father Time", as they have fondly nicknamed him, suddenly stops coming, Poirot believes that he might have picked up the one essential clue that could shed light on this mysterious man. Could what Old Father Time ordered as his final meal provide the key?

The recently married Alix Martin is obsessed with a recurring dream of her new husband's murder. Each time she can see the murderer clearly, and it's the mild-mannered man she had previously been engaged to, taking his revenge. But, what's worse is that at the end of the dream she thanks the murderer. Perplexed, Alix tries to calm herself by spending time in the garden of her picturesque cottage. But her gardener confuses her further by wishing her well on her trip to London - a trip which Alix knows nothing about. Now Alix is scared: Is the gardener imagining things, or is she?

The rather disgruntled pair of Tommy and Tuppence are sequestered in the Grand Adlington Hotel, having made a pig's ear out of their latest case. But, while mournfully sipping cocktails, with Tommy oddly dressed as a parson, they are gleefully accosted by their old acquaintance Mr. Bulger, who has London's most beautiful stage actress, Gilda Glen, in tow. Featherbrained and a little confused, Gilda takes Tommy for a real clergyman and scrawls out a desperate note to meet him away from the hotel. While Tommy and Tuppence mull over the note, in storms an old flame of Gilda's, claiming he wants to wring someone's neck.